[Thermal Mass]

Before we built our WFO (pizza oven) we used the pizza stone a lot.
Timing and constancy (heat qty/type) is key to getting a perfect crust every time. (an infra red thermometer is very helpful.)
*do not wash the stone, ever* It will take much longer to pre-heat and can cause it to crack.

IMO 700 deg. is too hot, you will get a cooked crust and only warmed toppings. We cook pizzas in the WFO at not much higher than 600 deg. deck temps.
Yes it can be done hotter but must be watched closely and have the right dough.

I really like the idea of two fire brick under the stone, a little more "thermal mass" and puts the toppings closer to the lid.

Look for a dough recipe that has a little more moisture, this will cook a little longer without burning. A few rolled out "samples" will help get the timing and temp right.

Have fun. Pr0n wanted!!